Collectively, Chicago region forest preserves, including those in Lake and Cook counties, spend more than $1 million annually to eradicate buckthorn and honeysuckle, two of the area's most invasive plants, according to the Chicago Region Trees Initiative.

But the population of these species, especially buckthorn, continues to expand, said Matt Ueltzen, a restoration ecologist with the Lake County Forest Preserves.

Indeed, 42 percent of Lake County's tree landscape is buckthorn, the highest percentage in the region, with Cook County coming in second at 32 percent, according to the initiative. Those figures include not only the natural areas managed for the public by forest preserve districts and others, but also land owned by parks, businesses and homeowners.

Seventy percent of the trees in our region are on private land, according to Lydia Scott, director of the Chicago Region Trees Initiative, which focuses on Cook, DuPage, Kane, Kendall, Lake, McHenry and Will counties.

That's why the initiative, founded by the Morton Arboretum to create a healthy, more diverse urban forest, is enlisting landowners as well as landscapers to help battle buckthorn.

The group hosted the first of two workshops in Lindenhurst on Feb. 21 to educate homeowners, landscape contractors, municipality representatives and others in the region ways about how to eradicate buckthorn — as well as why it's necessary.

The Chicago Region Trees Initiative (chicagorti.org) provided information for identifying buckthorn, an invasive species that overwhelms native plants and trees in Lake County and the metro area:

•Grows 25 feet tall

•Forms thickets

•Bears glossy-green leaves, persisting into winter

•Produces blue...

(Sheryl DeVore)

Natural area land managers can remove all the buckthorn they want, but if homeowners adjacent to those properties as well as throughout the region don't, birds will eat the berries and deposit the seeds back into the natural areas and start the cycle again.

"It's something we need to focus on — what's happening on private property," said Scott, who lives in Lincolnshire and works to keep buckthorn out of her yard.

"Our goal is to establish buckthorn-free zones in the region," she said. The group also hopes to inspire those homeowners who already remove buckthorn from their land to convince neighbors to join the movement.

Two types of non-native buckthorn grow in the region. Common buckthorn is more prevalent and found in many landscapes. Glossy buckthorn is less common and grows in wet areas. The seminar focused on the common variety.

Forest preserve districts consider buckthorn a major threat to the health of natural areas. For example, in its 100-year master plan, the Lake County Forest Preserves announced a goal to eradicate buckthorn on district lands through restoration and management, as well as reduce the plant's population by 50 percent throughout Lake County through partnerships and outreach.

Buckthorn was introduced in the 1880s to the U.S. as an ornamental plant. It quickly spread, taking over native plants and disturbing natural ecosystems.

Nearly all of Brandon Losey's clients have buckthorn on their properties. Losey, designer and sustainability director for Ringers Landscaping in Fox River Grove, tells his clients why they should have it removed and what to plant instead.

It's not always an easy sell. Buckthorn — which retains its leaves well into early winter — is seen as privacy screen for landowners. Losey works to convince them he can create the same effect using native plants.

First, however, he wants them to know why buckthorn is bad.

"Driving around, it's heartbreaking to see how much buckthorn and honeysuckle are out there," he said.

Sheryl DeVore / News-Sun

Matt Ueltzen, at left, a restoration ecologist with the Lake County Forest Preserves, shows ways to identify a type of honeysuckle that’s almost as invasive as buckthorn.

Matt Ueltzen, at left, a restoration ecologist with the Lake County Forest Preserves, shows ways to identify a type of honeysuckle that’s almost as invasive as buckthorn. (Sheryl DeVore / News-Sun)

Northern Illinois area land managers and biologists have known for decades that buckthorn crowds out other plants, including native ones — turning a diverse area of plants and animals into a thicket of just one species.

"Buckthorn is a prolific berry producer. Birds eat the berries, but it's not nutritious for them. It causes them to have diarrhea," said Scott. Birds transfer the seeds to other places, where the plant starts growing.

Recent studies are showing the invasive plant is affecting the landscape in even more profound ways.

At Middlefork Savanna Forest Preserve in Lake Forest, according to Ueltzen, the bare soil beneath a buckthorn thicket is adding sediment to an adjacent river, polluting the water. The district is working to restore the area, he said.

In addition, salamanders and snakes use leaf litter as habitat, and when an area is overtaken by buckthorn, they have no place to go, he said.

Research at MacArthur Woods near Vernon Hills has shown that a chemical in buckthorn can kill or cause malformations in amphibians, including blue-spotted salamanders and frogs, he said.

Removal techniques

Selling buckthorn has been illegal since the 1930s in the region, according to Losey. But it hasn't been easy to get rid of what's already growing. It requires hard work and can be costly, he said, so he tries to work within clients' budgets to slowly remove the buckthorn and replace it with native plants.

The first step is removing the plant — mostly done by cutting it down to the stump. But Losey said that if you just cut it back and do nothing else, "it can explode into a huge monster of a plant."

That's why land managers apply herbicides on the buckthorn's stumps.

"If you don't herbicide buckthorn, it's 90 percent likely it will come back," said Jim Anderson, director of natural resources for the Lake County Forest Preserves.

Sheryl DeVore / News-Sun

Common buckthorn is an invasive plant in the Chicago region, taking up more than 40 percent of Lake County's tree landscape.

Common buckthorn is an invasive plant in the Chicago region, taking up more than 40 percent of Lake County's tree landscape. (Sheryl DeVore / News-Sun)

Anderson said the key is to read labels, wear appropriate clothing — including long pants and shirts, shoes and socks and chemical-resistant gloves — and apply just a little herbicide on the cambium, which is the outer layer of the stump.

Products can be purchased at some garden centers, but those that are ready-to-use aren't effective, land managers at the seminar agreed. Scott recommended products from Conserv FS in Wauconda.

Still, some people don't like the idea of using herbicides. Losey said other methods involve digging the entire plant out, including the roots, a process that can be costly and time-consuming. Another method is to place black plastic bags over the stumps until it's certain the buckthorn won't return.

"But that's a lot of work, and you're talking about a lot of plastic," he said.

Another suggestion is to have buckthorn ground into wooden chips and placed over the area to prevent others from emerging, until you're ready to start new plantings of different species.

Whatever is done, landowners need to monitor the area, pulling any new buckthorn sprouts, he said. It all takes time and a plan, Losey said, and it might be several years before you see results.

To see a Lake County Forest Preserves success story on how removing buckthorn transforms an area, Ueltzen suggested visiting Broberg Marsh in Wauconda. Once overgrown with buckthorn, the area now has open views of wetlands where uncommon birds breed, he said.

Losey said when he moved into his Barrington home, his property was riddled with buckthorn. Before he got rid of it, he told his neighbors what he was doing and why. He explained that in a few years, there will be just as much of a screening effect with more diversity and likely more wildlife, including birds and butterflies. Education and communication is key, he said.

Homeowners like Marcia Jendreas are working to not only keep buckthorn out of her property, but also helping friends, relatives and neighbors do the same.

A master gardener and master naturalist through the Univeristy of Illinois, Jendreas said she tells people that buckthorn prevents other things from growing.

"If they're using it as a privacy hedge, I convince them to take out a little at a time, and I suggest native shrubs to replace, like elderberry and viburnums," she said.

On her own property in Prospect Heights, she cuts the buckthorn and then immediately herbicides it, she said.

Her daughter is moving to Barrington Hills and "there's lots of buckthorn on the property. She's gung-ho to get rid of it," and she will be helping, Jendreas said.

Sheryl DeVore / News-Sun

A buckthorn plant can be identified by revealing its yellow sapwood. The invasive species overwhelms other vegetation, and its shallow root systems and thin leaf litter also affect the region's ecosystem in negative ways.

A buckthorn plant can be identified by revealing its yellow sapwood. The invasive species overwhelms other vegetation, and its shallow root systems and thin leaf litter also affect the region's ecosystem in negative ways. (Sheryl DeVore / News-Sun)

Sandy Bemis, a golf course superintendent for the Round Lake Area Park District, said the district understands the need to eradicate invasive species such as buckthorn on its properties. "We try to do as much as we possibly can," she said. After the seminar, she said she planned to write a specific plan on dealing with buckthorn.

"It's an ongoing process" to remove it, said Joan Keyes, president of the Lincolnshire Garden Club. She added it can be expensive, and praised her landscaper for helping her budget the removal of buckthorn on her land.

Garden club member Kay Siess ,who lives in Deerfield, said buckthorn is "everywhere. But if we are all vigilant about helping, we can keep it in check."

Still, not every neighbor wants to join the crusade. Jan Stefans, also a garden club member, said someone who lives on her block plants buckthorn in his yard, digging it up from other areas. She's not sure what to do, she said, because "it's his property," and she knows converting everyone to become buckthorn warriors isn't possible.

Losey said communication can help, adding that "it's going to take all of us to tackle this issue."